Wiper assembly for vehicles

ABSTRACT

A wiper assembly for vehicles, in which the intermittent operation of a wiper motor is effected by using a coupling mechanism, such as a fluid coupling mechanism, the maximum transmitting torque of which varies in proportion to the rate of rotation.

United States Patent Ori [451 Aug. 15, 1972 WIPER ASSEMBLY F OR VEHICLESReferences Cited [72] lnventor: Takaaki Ori, Nagoya, Japan UNITED STATESPATENTS [73] Assignee: Nippondenso C Ltd, Ai hpk 3,118,164 1/1964 Deibelet al. ..318/443 Japan 3,168,758 2/1965 Oishei et a1 ..318/443 X [22]Filed: July 12, 1971 FOREIGN PATENTS OR APPLlCATlONS [21] Appl. No.:161,626 1,574,000 6/1969 France ..318/443 [30] Foreign ApplicationPriority Data Primary Examiner-Benjamin Dobeck ug apan 45/68140 ABSTRACT2 A for vehicles in the inte -mit- [5 hit. Cl. tent opgration f 3 wiperm t r is effected using a [58] Field of Search ..318/443, l22; couplingmechanism, such as a fluid p g v mechanism, the maximum transmittingtorque of which varies in proportion to the rate of rotation.

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sum 9 0r 9 2/ /a g F 32 a \g 4 w a \2 i- 25 III! INVENTOR Tmrnnm mATTORNEY S WIPER ASSEMBLY FOR VEHICLES This invention relates to a wiperassembly for vehicles which is very useful in a drizzling rain andcontinuously operable iterrnittently.

Conventional wiper assemblies of the type described include one whichcomprises an electronic intermittent operation mechanism utilizingsemiconductors such as transistors. This type of wiper assembly,however, has the disadvantages that a large number of component partsand many soldering operations required in assembling work add to thecost of the wiper assembly, and that the characteristic change of thesemiconductors due to a temperature change results in a variation in theinterval of intermittent operations. There has also been known a wiperassembly of the type comprising a bimetallic intermittent operationmechanism, but this type is also unsatisfactory in that the productionand adjustment of a bimetal requires a skill and in that bimetalsheating means provides the danger of fire.

In order to eliminate the above-described disadvantages, the presentinvention has for its object the provision of a wiper assembly forvehicles, in which a wiper motor is intermittently operated by using acoupling mechanism, such as a fluid coupling, in which the maximumtransmitting torque varies in proportion to rotation, whereby anintermittent operation mechanism can be composed of a relatively lessnumber of component parts which can be fabricated by machining and henceare adapted for mass production; and which, therefore, can be producedeasily at a low cost and is capable of intermittent operation with goodtemperature characteristic. 4

The present invention will be described in detail hereunder withreference to a plurality of typical embodiments thereof shown of in theaccompanying drawing. In the drawing,

FIG. 1 is a sectional view of an embodiment of the wiper assemblyaccording to the present invention;

FIG. 2 is an exploded perspective view of the wiper assembly of FIG. 1;

FIGS. 3 and 4 are electric circuit diagrams of the wiper assembly;

FIGS. 5 and 6 are sectional view of another embodiment of the invention;

FIGS. 7 and 8 are a plan view of the cap and a front elevational view ofthe relay respectively;

FIG. 9 is an electric circuit diagram of the wiper assembly of FIGS. 5and 6;

FIG. 10 is a sectional view showing the construction of the wiperassembly of FIGS. 5 and 6;

FIG. 1 l is an exploded perspective view of the essential portion of theconstruction shown in FIG. 10;

FIG. 12 is a sectional view showing the construction of the wiperassembly; and

FIG. 13 is a plan view of the cap.

An embodiment of the invention shown in FIGS. 1 and 2 will be describedat first. FIG. 1 is a sectional view showing the mechanical constructionof one embodiment of the invention and FIG. 2 is an exploded perspectiveview of FIG. 1.

In FIGS. 1 and 2, reference numeral 1 designates a worm gear on theoutput side of a wiper motor 24, which is composed of an output shaft laand a resinmade worm gear lb. Reference numeral 2 designates a worm gearformed on the armature shaft of the motor 24. The worm gear lb, as shownin FIG. I, has a recess A formed at the center of one end face thereofand a metal cap 4 is secured to the worm gear lb by means of screws 8,covering said recess A. A disc impeller 3 is disposed in the recess Aand further, a viscous fluid, such as silicon oil, of which viscosity isnot susceptible to temperature change is sealed in said recess A. Therecess A, the impeller 3 and the viscous fluid together form a fluidcoupling. An impeller shaft 3a is electrically insulated from the cap 4by means of a resin-made bearing 6 force-fitted in the cap 4, and issmoothly rotatable in said coupling. An oil seal 7 is provided toprevent the fluid in the recess A from leaking to the outside. Betweenthe cap 4 and the worm gear lb is disposed an O-ring-shaped oil seal 5to prevent a fluid leakage, said oil seal 5 being fitted in agrooveformed in the end face of the worm gear. An insulating plate 23 is fixedin a housing 20 and a metallic elastic brush 9 is fixed on saidinsulating plate 23 at a portion 9a for slid ing movement on the endface of the cap 4. Further, a metallic elastic member 9' is secured tothe insulating plate 23 by means of a rivet 15 for sliding movement onthe outer peripheral surface of the cap 4. The cap 4 is formed with anotch 4a in the peripheral edge thereof as shown in FIG. 2 and aprojection 1b of the worm gear lb is received in said notch 4a. It willthus be understood that the brushes 9 and 9 are electrically insulatedfrom each other only when the brush 9' is located at the position of thenotch 4a in the cap 4 incident to rotation of the worm gear lb.

On the opposite side of the insulating plate 23 relative to the cap 4 isdisposed a metallic helical spring 11 with one end anchored to a fixingstud 10 which is press-fitted into the impeller shaft 3a. Thus, thehelical spring 11 is wound up incident to rotation of the impeller 3.The other end of the helical spring 11 is secured to a metallic bracket13 which is fixed on the insulating plate 23 by means of a rivet 15. Apoint arm 12 is secured to the stud l0 and a fixed electric contact 12ais provided on said arm 12. The contact 12a on the arm 12 is opposed bya contact which is provided on a bracket 14 secured on the insulatingplate 23 by means of a rivet 15. Reference numeral 18 designates a coverhaving an insulating bush l7 and a shaft 16 is received in said bush 17in tight engagement therewith so that said shaft 16 will not be allowedto rotate under a torque smaller than a certain value. A stopper 16 isfixedly mounted on the shaft 16, which serves to stop the rotation ofthe point arm 12. Reference numeral 19 designates an electromagneticrelay having an electric. construction as shown within the block 19 inFIG. 3 or 4 to be described later. The output shaft la of the worm gear1 extends through the housing 20 and is held against movement in thedirection of thrust by means of a clip 21. Reference numeral 22designates a classic arm connected with a wiper link mechanism, and 24designates a wiper motor unit.

The electric circuit of the wiper assembly constructed as describedabove will be described with reference to FIGS. 3 and 4. Referring firstto FIG. 3, reference numeral 4 indicates the cap shown in FIGS. 1 and 2described above and 24 indicates the wiper motor which is a compoundmotor comprising an annature 24a, a shunt coil 24b and a series coil24c.

The block B is the fluid coupling mechanism and the contact mechanismdescribed above, and the block 19 is the electromagnetic relay. Anormally-open contact 19b of the electromagnetic relay 19 is connectedin parallel with the contact 12a on the point arm 12 and the fixedcontact 140 on the bracket 14. The contact 19b is closed when a coil 19ais energized by the operating current for the wiper motor 24. Thebrushes 9, 9' cooperate with the cap 4 to provide a switching mechanism.Namely, the brushes 9 and 9' are electrically disconnected from eachother to stop the motor 24 only when said brush 9' is located inregister with the notch 4a of the cap 4, thus forming the so-calledautomatic fixed position stopping contact mechanism. The block D is awiper switch having a movable member 39. The movable member 39 isoperated by an operating knob 38 and consists of electrically insulatedtwo movable elements 39a and 39b. The arrangement is such that contactsD D only are closed when the movable member 39 is in a position a;contacts D D only are closed when the movable member 39 is in a positionb; and contacts D D only are closed when the movable member 39 is in aposition 0. Reference numeral 37 designates an ignition key switch, 36 afuse and 35 a car battery providing a power source.

The wiper assembly of the invention having the electric circuitdescribed above operates as follows: Namely, when the key switch 37 isin a closed position and the movable member 39 of the wiper switch D isin the position b, a current flows from the battery 35 through the keyswitch 37, the contacts D D, and the fixed bracket 13 to the helicalspring 11, and thence through the point arm 12 and the contacts 12a, 14ato the bracket 14. Because the contacts 12a of the point arm 12 isconstantly urged into contact with the contact 14a under the restoringforce of the helical spring 11. From the bracket 14, the current issupplied through the relay coil 19a to the wiper motor 24 and thus saidwiper motor 24 is set in motion. At the same time, the relay coil 19a isenergized, so that the relay contact 19b is closed and the worm gear 1bis rotated by the wiper motor 24. In this case, the impeller 3 which isenclosed in the recess A of the worm gear lb, together with the viscousfluid, rotates under the rotational torque of the worm gear 1b. Themaximum transmitting torque varies in accordance with the rate ofrotation of the worm gear 1b and and theoretically is proportional tothe square of said rate of rotation. Since the worm gear 1b of the wipermotor 24 therefore rotates at a relatively high rate, a relativelystrong torque is transmitted to the impeller and the helical spring 11is wound up under said torque. Further, as a result of the rotation ofimpeller 3, the contact 12a on the point arm 12, fixed to the shaft 3 ofsaid impeller, is disconnected from the contact 14a on the bracket 14.

In this case, the current is continuously supplied to the wiper motor 24through the contact 19b, since said contact 19b is held closed as statedabove even after the contacts 120 14a have been disconnected from eachother. Thus, the wiper motor 24 continues its rotation. Now, when thecap 4 overlying the worm gear 1b rotates, together with said gear lb, toa position to connect electrically the brushes 9, 9' with each other,the opposite ends of the relay 19 are electrically shorted and thepotentials at said ends are equalized, so

that the current no longer flows through the relay coil 19a.Consequently, the coil 19a is deenergized and the contact 19b is opened,and the wiper motor 24 continues its operation with the current suppliedthereto through the the brushes 9, 9'. The rotation of the point arm 12is limited at this point, by the stopper 16. However, since the wormgear lb continues to rotate under the drive of the wiper motor 24, theresult is that the impeller 3, which has been stopped by the stopper 16through the point arm 12, makes idling in the viscous fluid. When theworm gear lb completes its full turn, the cap 4 is again located in theposition shown in FIG. 3, so that the brushes 9, 9' are opened again andthe current supply to the wiper motor 24 is interrupted, resulting instoppage of said motor. In this case, the armature 24a of the motor 24tends to rotate continuously under the force of inertia but is stoppedabruptly under the effect of dynamic braking, since a short circuit isformed across the opposite ends of the armature 240 due to closure ofthe contacts D D of the wiper switch D. Therefore, in no cases will thebrush 9' be brought into electrical contact with the brush 9 uponpassing over the notch 4a, and will the motor 24 not be stopped, but themotor can be stopped positively in a fixed position. Upon stoppage ofthe motor 24, the impeller which has been restrained from rotation bythe stopper 16', idles in the reverse direction within the recess Aunder the biasingfforce of the helical spring 1 1 which has previouslybeen wound up. Because, since the maximum transmitting torque of thefluid coupling mechanism is proportional to the square of the rate ofrotation due to the characteristic of fluid, as stated above, when theworm gear lb on the input side of said fluid coupling mechanism stopsrotating, the maximum transmitting torque of said fluid couplingmechanism becomes extremely small and the impeller 3 is returned by theslight force or the slight spring load of the helical spring whileidling slowly being subjected to the braking force of the viscous fluid.As a result, the contact 12a on the point arm 12 is again brought intocontact with the contact 14a on the bracket 14 and hence the wiper motor24 is again set in motion. The abovedescribed operation is repeated,causing the wiper to make an intermittent operation highly suitable in adrizzling rain.

The interval of the successive intermittent operations is provided bythe period from the time when the wiper motor 2 is stopped to the timewhen the contact 12a on the point arm 12 is brought into contact withthe contact on the bracket 14 as a result of slow idling of the impeller3 under the biasing force of the helical spring 11. This interval can beextended by increasing the rotatable angle of the point arm 12 or can beshortened by decreasing said rotatable angle, upon chang ing theposition of the stopper 16' by rotating the shaft 16.

When the movable member 39 of the wiper switch D is located in theposition a, the current is supplied from the battery 35 directly to thewiper motor 24 and, therefore, said motor operates continuously. In thiscase, the point arm 12 is allowed to rotate only through a certain angleby the stopper 16' and held against rotation after rotating through saidlimited angle. However, the continuous rotation of the worm gear lb willnot cause any mechanical or electrical trouble because the result isonly that the impeller idles in the viscous fluid.

In the circuit of FIG. 3, however, there may be the fear of the contacts12a, 14a being worn out due to the fact that the operating current flowsthrough the wiper motor 24 for a very short period until the contact 19bis closed through said contacts 12a, 14a. In this view, the circuitarrangement shown in FIG. 4 is recommendable, particularly for a wiperassembly which is required to be serviceable for an extended period.

The difference between the circuit arrangements of FIGS. 3 and 4 liesonly in that the electromagnetic relay [9 in FIG. 3 is replaced by onegenerally iddicated by numeral 19'. This electromagnetic relay 19includes, as an exciting coil, a voltage coil l9'c in addition to thecurrent coil 19'a, and both coils l9'a, 19's are wound in the cumulativefashion. In this circuit arrangement, the current supplied through thecontacts 12a, 14a flows initially through a path extending from thevoltage coil l9 'c to the wiper motor 24. However, because of the highimpedance of the voltage coil l9'c, the wiper motor 24 is not actuateddue to a large voltage drop in said coil 19'c. On the other hand, therelay contact l9b is closed to energization of the voltage coil l9'c,and a circuit is formed extending from the contact l9b through thecurrent coil l9'a to the wiper motor 24, through which the wiper motor24 is set in motion. The subsequent operation is the same as that of thecircuit of FIG. 3 and will not be reiterated herein. In short, thecircuit arrangement of FIG. 4 differs from that of FIG. 3 only in thatthe voltage coil l9'c which is energized with a slight current, is addedto the circuit of FIG. 3, for the purpose of protecting the contacts12a, 14a. By the addition of the voltage coil l9'c, the contacts 12a,14a pass only a slight current therethrough and hence inexpensivecontacts of small current capacity can be utilized for said contacts12a, 14b and the useful life of the circuit can be substantiallyprolonged.

Another embodiment of the present invention will be described withreference to FIGS. 5 8 hereunder. In the preceding embodiment, the motorunit and the intermittent operation controlling mechanism are integralwith each other, but in this embodiment they are separated from eachother so that the intermittent operation controlling mechanism may belocated adjacent the instrument panel even when the motor unit cannot belocated in a position accessible to the operator due to a limited spaceor other reasons, and the interval of the successive intermittentoperations may be adjusted easily by controlling remotely said motorunit from said controlling mechanism. In the embodiment of FIGS. 5 8which will be described practically hereunder, the same referencenumerals as those in the preceding embodiment designate the same partsand the descriptions of these parts will be omitted. FIG. 5 shows themotor unit provided with an automatic fixed position stopping contactmechanism. In this motor unit, a plate-like electric cam4-l as shown inFIG. 7 is fixed on one end face of the worm gear 1b, by means of claws4-1b formed at the inner peripheral edge thereof, said electric cam 4-1having a notch 4-la formed at a portion thereof. The brushes 9, 9' aresupported by a cover 25 through an insulating member 25a, for contactwith the electric cam 4-l. The arrangement is such that the brushes 9,9' are electrically disconnected from each other only when the brush 9'is located within the notch 4-la of the electric cam as shown in FIG. 7.Reference numeral 30 designates a flexible shaft connecting the shaft isof the worm gear lb with a fluid coupling housing 10 to be describedlater, and having square keys 29 at the opposite ends thereof which arereceived in said shaft la and said housing 1c respectively. Referencenumeral 31 designates a flexible tube surrounding the flexible shaft 30and having the opposite ends thereof secured to the cover 25 and a cover27 of the interrnittend operation controlling mechanism to be describedlater, respectively.

FIG. 6 shows the intermittent operation controlling mechanism. The fluidcoupling housing 10 is driven by the worm gear la of the motor unitthrough the flexible shaft 30. The housing 1c is formed with a recess A,in which the viscous fluid and the impeller 3 are sealed by means of acap 4-2. The fluid coupling mechanism is composed of the housing 10, theimpeller 3 and the viscous fluid. Reference numeral 23' designates aninsulating plate, 26 a housing of the controlling mechanism, 26' afitting by which said housing is secured to the instrument panel or thelike, 28 a bearing, and 33 and 34 electric conductors by which theintermittent operation controlling mechanism is electrically connectedwith a relay 19" provided separately and shown in FIG. 8, the electriccircuit of said relay 19" being similar to that of the relay 19 or 19 inthe preceding embodiment. Reference numeral 16" designates an adjustingknob fixed on the shaft 16.

It will be obviously understood that this embodiment of the inventionconstructed as described above operates in the same manner as thepreceding embodiment when the electric circuit is arranged as in FIG. 3or 4. The foregoing description has been given on a winding field-typewiper motor, but in case of a permanent magnet field-type wiper motorthe dynamic braking circuit is different from that of the windingfield-type wiper motor and hence a slight change must be made to theelectric circuit of the wiper assemblies of the invention describedabove. The permanent magnet field-type wiper motor will be describedhereunder with reference to FIG. 9 in which the same parts as those inthe preceding embodiments are indicated by the same reference numeralsand will not be described again. Reference numeral 24b designates apermanent magnet field of the wiper motor, and reference character Ddesignates a wiper switch which is arranged such that the contacts D' D,and D';, thereof are closed when the movable member 39 is in theposition a; the contacts D' D' are closed when the movable member 39 isin the position b; and the contacts D',,, D 1 are closed when themovable member 39 is in the position c. Reference numeral 4 designates acap corresponding to the cap 4 in FIG. 3, and 9, 9' and 9" designatebrushes arranged for contact with said cap 4'. The cap 4 is formed witha notch 4'a and a projection 4'c, by which the brushes 9, 9" areelectrically connected with each other at first and then disconnected inthe meantime and again connected with each other a while later, duringone revolution of said cap 4, and returned to the original positions atthe point when said cap has made a complete turn. Reference numeral 19"designates an electromagnetic relay which is composed of cumulativelywound current coil l9"a and voltage coil 19"c, and a normally-opencontact 19"b and a normally-closed contact 19"d which are operated wheneither one of said coils 19"a, 19"c is energized, respectively.

The wiper assembly of the invention having the circuit arrangementdescribed above, operates in the following manner: Namely, when the keyswitch 37 is held in a closed position and the movable member 39 of thewiper switch D is located in the position a, a circuit is formedextending from the battery 35 to the ground through the relay contact19"d, the brush 9", the brush 9, the wiper switch D', the contact 14a onthe bracket 14, the contact 12a on the point arm 12, the helical spring11 and the voltage coil 19"c. Therefore, when the contact 19"b is closedin this state, the contact 19"d is opened concurrently, so that acircuit extending from the battery to the ground through the armature24a, the wiper switch D', the relay contact 19"b and the current coil19"a is formed, setting the wiper motor 24 in motion. Consequently, thecap 4" is rotated and the brushes 9, 9 are electrically disconnected andthen connected with each other, so that a circuit is formed now,extending from the battery 35 to the ground through the armature 24a,the wiper switch D, the brush 9 and the brush 9, and the opposite endsof the series circuit of the coil 19"a and contact 19"b of the relay19"are electrically shorted, rendering said relay 19" inoperative,whereby the contact 19"b is opened and the contact 19"c closed. Here,the wiper motor 24 continues its rotation while being supplied with thecurrent through said circuit, and the helical spring 11 is wound upunder the torque of the worm gear lb transmitted thereto through thefluid coupling mechanism C, whereby the contact 12a on the point arm 12is disconnected from the contact 14a on the bracket 14. The rotation ofthe point arm 12 is limited by the stopper l6 and the impeller in thefluid coupling mechanism C rotates idly therein. The cap 4" returns tothe position of FIG. 9 upon completion of the complete turn of the wormgear lb and the brushes 9, 9' are electrically disconnected from eachother. As the same time, the brushes 9, 9" are electrically connectedwith each other, with the result that the current supply circuit for thewiper motor is broken and a short circuit is formed across the oppositeends of the armature 24a. The wiper motor 24 is stopped abruptly by thedynamic braking action of the short circuit.

When the wiper motor 24 has been stopped, the point arm 12 is returnedto the original position, similar to the preceding embodiments, by thefunction of the fluid coupling mechanism C and the contact 12a thereonis brought into contact with the contact 14a on the bracket 14, wherebythe above-described operation is repeated again.

For reference, the mechanical construction of the subject wiper assemblywhich performs the abovedescribed operation will be described withreference to FIGS. 10 13. FIG. 10 shows a construction wherein the motorunit and the intermittent operation controlling mechanism are arrangedintegrally with each other. The difference of this construction fromthat of FIG. 3 lies in the fact that the brush 9" is secured to theinsulating plate 23 by means of the rivet l5 and the cap 4' is providedwith a projection 4'c as shown in FIG. 1 1. FIG. 12 shows the motor unitonly in the case wherein the motor unit and the intermittent operationcontrolling mechanism are provided separately from each other. Thedifference of this motor unit from that of FIG. 5 lies in the fact thatthe electric cam 4'1 is provided with a projection 4'-1c as shown inFIG. 13 and the brush 9" is secured to the cover 25 through aninsulating member 25a.

In each of the embodiments described above, the worm gear lb rests for acertain period of time on every rotation during the intermittentoperation and accordingly the wiper performs the wiping operation onceat a time. However, by reducing the rotational speed of the cap 4 (4) orelectric cam 4-1 (4l) by which the automatic fixed position stoppingcontact mechanism is operated, such that it makes one revolution duringtwo revolutions of the worm gear lb, it is possible to obtain two wipingoperations of the wiper at a time. Further, the interval of theintermittent wiping operation can be adjusted by varying the position ofthe stopper 16' but may also be adjusted by varying the viscosity of theviscous fluid, the spring constant of the helical spring, the diameterof the impeller 3 or the gap between the impeller 3 and the housing.

As described herein, according to one aspect of the invention a wiperassembly for vehicles, having a wiper motor connected to a power sourcethrough automatic fixed position stopping contacts, comprises a couplingmechanism having its driving side connected with the output shaft ofsaid wiper motor and being of such character that the maximumtransmitted torque thereof varies in proportion to the rate of rotationlike that of a fluid coupling mechanism, a helical spring provided onthe driven side of said coupling mechanism and wound up by the rotationof said wiper motor, a main contact provided on the driven side of saidcoupling mechanism and opened by the operation of said wiper motor, anda relay which is excited from the time when said main contact is closed,thereby to form a current supply circuit for said wiper motor and also aself-holding circuit, said current supply circuit for the wiper motorformed by said relay being connected in parallel with said automaticfixed position stopping contacts, whereby when the current supplycircuit for the wiper motor is formed on actuating of the relay and saidwiper motor is set in motion, the helical spring is wound by through thecoupling mechanism, and at the same time, the main contact is opened andthe automatic fixed position stopping contacts are closed, so that therelay is deenergized and the stopping contacts are opened to stop thewiper motor. Here, the driven side of the coupling mechanism is rotatedidly under the baising force of the helical spring which has thus beenwound up and after a set period of time, the main contact is againclosed and the motor is set in motion through the relay. This, it ispossible to obtain an intermittent operation which is highlyadvantageous in a drizzling rain. Further, the wiper assembly of theinvention involves a more number of machined parts than in theconventional one comprising an electronic intermittent operationmechanism, so that by producing these parts on the mass productionbasis, the cost of the wiper assembly can be reduced drastically.Furthermore, as compared with the conventional bimetallic intermittentoperation mechanism, the intermittent operation mechanism used in thesubject wiper assembly is composed of parts the majority of which arethose commonly used heretofore, such as a helical spring used inspeedometers of automobiles and the parts of fluid mechanisms used as ashock absorbing mechanism for the speedometers. Therefore, the wiperassembly of the invention has the remarkable advantage that it can beproduced easily and at a low cost, without encountering any particulardifficulty. In the fluid coupling mechanism of the subject wiperassembly is used a fluid, such as silicon coil, the viscosity of whichis not varied by temperature change. Therefore, there is the advantagethat the interval of the intermittent operation will not be changed bythe ambient temperature. A further advantage of the subject wiperassembly is that, even when the driven side of the coupling mechanism islocked for some reasons, the slippage of the coupling mechanism occurs,thus precluding any serious trouble. According to another aspect of theinvention, the wiper assembly of the character described above isarranged such that the current which is conducted through a voltage coilof the relay only is led to the main contact and the operating currentfor the motor is not led thereto. Therefore, there is the advantage thata small-sized, inexpensive contact having a small current capacity canbe used for the main contact.

According to still another aspect of the invention, the wiper assemblyof the character described above further comprises a dynamic brakingcircuit which is closed when the automatic stopping contacts are opened,to electrically short the opposite ends of the wiper motor, and anormally-closed contact provided in the relay for breaking said dynamicbraking circuit, whereby when a permanent magnet-type motor is used forthe wiper motor, there can be achieved such advantages that the motorcan be stopped quickly by the function of said dynamic braking circuitand thereby the wiper can also be stopped positively in a set position,and that conduction of a shorting current through the dynamic brakingcircuit at the start of the motor can be avoided as said dynamic brakingcircuit is broken by the relay contact.

What is claimed is:

1. A wiper assembly for vehicles, having a wiper motor connected to apower source through automatic fixed position stopping contacts, whichcomprises a coupling mechanism having its driving side connected withthe output shaft of said wiper motor and being of such character thatthe maximum transmitting torque thereof varies in proportion to the rateof rotation like that of a fluid coupling mechanism, a helical springprovided on the driven side of said coupling mechanism and wound up bythe rotation of said wiper motor, a main contact provided on the drivenside of said coupling mechanism and opened by the operation of saidwiper motor, and a relay which is excited from the time when said maincontact is closed, thereby to form a current supply circuit for saidwiper motor and also a self-holding circuit, said current supply circuitfor the wiper motor formed by said relay being connected in parallelwith said automatic fixed position stopping contacts.

2. A wiper assembly for vehicles, having a wiper motor connected to apower source through automatic fixed position stopping contacts, whichcomprises a coupling mechanism having its driving side connected withthe out ut shaft of said wiper motor and being of such charac er thatthe maximum transmitting torque thereof varies in proportion to the rateof rotation like that of a fluid coupling mechanism, a helical springprovided on the driven side of said coupling mechanism and wound up bythe rotation of said wiper motor, a main contact provided on the drivenside of said coupling mechanism and opened by the operation of saidwiper motor, and a relay composed of a voltage coil which can beenergized through a wiper switch when said main contact is closed, anormally-opened contact which is closed when said voltage coil isenergized and a current coil which is connected in series with saidnormally-opened contact; the series circuit of said voltage coil of saidrelay and said main contact, the series circuit of said normally-openedcontact and said current coil, and said automatic fixed positionstopping contacts being connected in parallel.

3. A wiper assembly for vehicles, having a permanent magnetic field-typewiper motor connected to a power source through automatic fixed positionstopping contacts, which comprises a coupling mechanism having itsdriving side connected with the output shaft of said wiper motor andbeing of such character that the maximum transmitting torque thereofvaries in proportion to the rate of rotation like that of a fluidcoupling mechanism, a helical spring provided on the driven side of saidcoupling mechanism and wound up by the rotation of said wiper motor, amain contact provided on the driven side of said coupling mechanism andopened by the operation of said wiper motor, and a relay energized fromthe time when said main contact is closed, thereby to form a currentsupply circuit for said wiper motor and also a self-holding circuit,said current supply circuit for said wiper motor formed by said relaybeing connected in parallel with said automatic fixed position stoppingcontacts and further there being provided a dynamic braking circuitwhich is closed when said automatic fixed position stopping contacts areopened, to electrically short the opposite ends of said wiper motor, andsaid relay having a normally-closed contact for opening said dynamicbraking circuit.

1. A wiper assembly for vehicles, having a wiper motor connected to apower source through automatic fixed position stopping contacts, whichcomprises a coupling mechanism having its driving side connected withthe output shaft of said wiper motor and being of such character thatthe maximum transmitting torque thereof varies in proportion to the rateof rotAtion like that of a fluid coupling mechanism, a helical springprovided on the driven side of said coupling mechanism and wound up bythe rotation of said wiper motor, a main contact provided on the drivenside of said coupling mechanism and opened by the operation of saidwiper motor, and a relay which is excited from the time when said maincontact is closed, thereby to form a current supply circuit for saidwiper motor and also a selfholding circuit, said current supply circuitfor the wiper motor formed by said relay being connected in parallelwith said automatic fixed position stopping contacts.
 2. A wiperassembly for vehicles, having a wiper motor connected to a power sourcethrough automatic fixed position stopping contacts, which comprises acoupling mechanism having its driving side connected with the outputshaft of said wiper motor and being of such character that the maximumtransmitting torque thereof varies in proportion to the rate of rotationlike that of a fluid coupling mechanism, a helical spring provided onthe driven side of said coupling mechanism and wound up by the rotationof said wiper motor, a main contact provided on the driven side of saidcoupling mechanism and opened by the operation of said wiper motor, anda relay composed of a voltage coil which can be energized through awiper switch when said main contact is closed, a normally-opened contactwhich is closed when said voltage coil is energized and a current coilwhich is connected in series with said normally-opened contact; theseries circuit of said voltage coil of said relay and said main contact,the series circuit of said normally-opened contact and said currentcoil, and said automatic fixed position stopping contacts beingconnected in parallel.
 3. A wiper assembly for vehicles, having apermanent magnetic field-type wiper motor connected to a power sourcethrough automatic fixed position stopping contacts, which comprises acoupling mechanism having its driving side connected with the outputshaft of said wiper motor and being of such character that the maximumtransmitting torque thereof varies in proportion to the rate of rotationlike that of a fluid coupling mechanism, a helical spring provided onthe driven side of said coupling mechanism and wound up by the rotationof said wiper motor, a main contact provided on the driven side of saidcoupling mechanism and opened by the operation of said wiper motor, anda relay energized from the time when said main contact is closed,thereby to form a current supply circuit for said wiper motor and also aself-holding circuit, said current supply circuit for said wiper motorformed by said relay being connected in parallel with said automaticfixed position stopping contacts and further there being provided adynamic braking circuit which is closed when said automatic fixedposition stopping contacts are opened, to electrically short theopposite ends of said wiper motor, and said relay having anormally-closed contact for opening said dynamic braking circuit.